An anterior intervertebral connection device generally comprises a rigid osteosynthesis plate adapted to cover at least partially two consecutive vertebrae, in order to join them together. This osteosynthesis plate presents an anterior face and an opposite posterior face intended to be applied against the anterior face of the vertebrae. This plate is generally provided with two pairs of through holes, designed each to receive a screw intended to be anchored in the body of the vertebrae.
After implantation of such osteosythsis devices in patients, a phenomenon of avulsion or of partial extraction of the anchoring screws has been observed. This results in a risk of lesion or injury, particularly of the oesophagus and the pharynx.
The need is therefore felt to ensure blocking of the anchoring screws in order to avoid their leaving the osteosynthesis plate.
In an attempt to satisfy this need, document FR 2 740 321 has proposed an osteosynthesis device comprising, as means preventing extraction of the screws, a rigid counter-plate intended to be fixed on the anterior face of the osteosynthesis plate. The shape of this counter-plate is substantially similar to that of the osteosynthesis plate, so as to totally to cover all the anchoring screw heads. The counter-plate is fixed on the osteosynthesis plate with the aid of a screw adapted to screw in a tapping made on the osteosynthesis plate. The counter-plate thus constitutes a stop for the heads of the screws.
It must be considered that the operation of positioning these anti-extraction means is relatively long to carry out due to the phase of positioning of the counter-plate, followed by a phase of screwing the counter-plate on the osteosynthesis plate. Furthermore, the screw for fixing the counter-plate on the osteosynthesis plate risks unscrewing, resulting in the counter-plate moving away from the plate and thus in an avulsion of the anchoring screws. Moreover, it must be considered that the use of a rigid counter-plate presents relatively large dimensions capable of causing injuries or lesions.
It is therefore an object of the invention to overcome the drawbacks set forth hereinabove by proposing an intervertebral connection device designed to present an efficient and reliable means for blocking the anchoring screws, while being easy and quick to place in position.